Type bar action having combined cam latching and driving lever



Jan. 24, 1967 L. P. FRECHETTE 3,300,018

TYPE BAR ACTION HAVING COMBINED CAM LATCHING AND DRIVING LEVER Filed June 4, 1963 fiPw a ATTORNEYS United States Patent Ofifice Patented Jan. 24, 1967 3,300,018 TYPE BAR ACTION HAVING COMBINED CAM LATCHING AND DRIVING LEVER Leo P. Frechette, West Hartford, Conn., assiguor, by mesne assignments, to Royal Typewriter Company, Inc., New York, N.Y., a corporation of Delaware Filed June 4, 1963, Ser. No. 285,322 3 Claims. (Cl. 19717) This invention relates to an improved power operated type bar action for an electric typewriter and the like.

Prior actions of this nature have certain common characteristics. Thus any given one of them includes a manually depressible key lever, depression of which releases an eccentric or cam to engage a power roll resulting in oscillation of a power arm on which the cam is mounted. The principal variations in these prior actions lie in the mechanisms intervening the key lever and the cam whereby the engagement between the cam and power roll is effected. This invention particularly relates to such a mechanism although novel differences are incorporated in the cam and power arm.

It is accordingly among the objects of this invention to provide an action of the above nature that is structurally simple, light in weight, inexpensive, durable in use and reliable in operation. Other objects will be in part apparent and in part pointed out hereinafter.

In the drawing wherein there is shown a preferred embodiment of the invention and wherein similar reference characters refer to similar parts throughout the several views:

FIGURE 1 is a side elevation of the action in rest position;

FIGURE 2 is an isometric view of the cam latching and activating member by which engagement between the cam and power roll is effected; and

FIGURE 3 is a fragmentary active view similar to FIGURE 1 but showing the condition of the parts shortly after engagement between the cam and power roll resulting from depression of a type key.

Referring first to FIGURE 1, the action includes a key lever pivotally mounted on a cross shaft 11 supported on the machine frame. A lug 12 is formed on lever 10 and is located to engage the upper end 13a of one arm 13 of a bell crank 14 pivotally mounted on a cross shaft 15 carried by the machine frame. A return spring 15a holds arm end 1311 against lug 12.

A power arm, generally indicated at 17, includes a top ear 17a by which the arm is pivotally mounted on a cross shaft 18. The power arm also includes a foot 17b which may be connected in conventional manner to a type bar 24 by a link 19. Depending from the body 170 of power arm 17 is a yoke comprising legs 17d and 17e. Counterclockwise return movement of the power arm is effected by a return spring 20.

A cam, generally indicated at 21, is pivotally secured to power arm body 170 as by a rivet 22 and includes a short upwardly extending arm 21a, a body portion 2111 from which extends a lug 21c and a foot 21d. Cam 21 is normally biased clockwise to its FIGURE 1 rest position by a return spring 23 the ends of which are respectively attached to arm 21a of cam 21 and power arm foot 17b, accidental clockwise movement of the cam relative to the power arm being prevented by the enagement of cam lug 21c with a shoulder 17 (FIGURE 1) formed on power arm 17. It will now appear that when cam foot 21d engages the power roll R the eccentricity of the cam foot riding over the, power roll results in counterclockwise movement of cam 21 about its pivot 22 and power arm 17 being rocked clockwise to pull link 19 to left as viewed in FIGURE 1. As the link is connected to a type bar 24 at pivot point 25 the bar is driven clockwise about its pivot 26 toward the typewriter platen (not shown). An adjustable impression controlling device 27 having a knock-off blade 28 is preferably provided in order to selectively control the driving time of cam 21, this being accomplished by setting blade 28 in or out thus controlling the counterclockwise stroke of the cam which impinges against the blade at the adjusted top limit of its stroke.

To cause positive movement of cam 21 into engagement with power roll R in response to depression of key lever 10, I have provided a combined cam latching and driving lever generally indicated at 30. As shown in FIGURE 3 this lever comprises a body 30a from which extend a latching arm 30b and a driving arm 300, the latter having a driving finger 30d extending therefrom and the end of the former comprising a latching finger 30e, the lever being pivotally mounted on the lower end of a power arm leg 17e by a pin 31 (FIGURES 1 and 3). The combined cam catching and driving lever 30 also includes an operating lug 30f and a hook 30g, the lug being provided to normally underlie a shoulder 16b formed on the end of bell crank arm 16 (FIGURE 1) and the hook serving to anchor one end of a return spring 32 whose other end is attached to the end of power arm leg 17d.

Operation When key lever 10 is depressed it rocks bell crank 14 clockwise pulling shoulder 16b of arm 16 downwardly to engage lug 30f of the combined cam latching and driving lever 30. This rocks lever 30 clockwise first to with draw latching driving finger 30e from cam lug 21c, and in timed relation to cause finger 30d of lever 30 to bear against a lobe 21e on cam 21 to positively rock the cam counterclockwise upon its pivot 22 so that the upper end of the cam foot 21d engages power roll R. The timing is provided by way of a gap between finger 30d of lever 30 and lobe 21e of cam 21. R011 R drives cam 21 counterclockwise and because of the cams eccentricity relative to roll R, power arm 17 is rocked clockwise about its pivot 18 to pull link 19 to the left thus swinging type bar 24 clockwise toward the platen. As the power arm 17 rocks clockwise it carries lever 30 with it withdrawing lug 30 of the lever from beneath shoulder 16b of bell crank arm 16 so that the lug assumes the position shown in FIGURE 3 from under and above shoulder 16b. Thus if key lever 10 is held depressed this relation of lug 30 and shoulder 16b comprises a by-pass to preclude repeat operation. In order to reset the action, key lever 10 must return sufiiciently to its normal position to allow latch lug 30f to slip under shoulder 16b. At the end of its drive travel cam foot 21d hits knock-off blade 28 and the type bar 24 continues its stroke in free flight to the platen during which time return spring 32 rocks member 30 counterclockwise about its pivot 31 to relatch cam 21. Thus the cam is positively unlatched and is positively driven into engagement with power roll by the action of the single lever 30 without reliance on springs or additional linkage to attain this end. Hence there is nothing to get out of adjustment after initial assembly and a highly etficient, longlived action is provided with an almost irreducible number of parts.

It will now be seen that with the above described action the several objects heretofore mentioned are attained in a thoroughly practical and efiicient manner.

As other embodiments of the invention are possible and as modifications of the one disclosed may be made, all without departing from the scope of the invention, it is to be understood that the foregoing should be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a type bar action for an electric typewriter including a power driven roll, a frame, a key lever pivotally mounted on said frame, a type bar pivotally mounted for movement from a rest position to a print position, a movable power arm pivotally mounted on said frame, a link connecting said type bar with said power arm, a return spring biasing said power arm and type bar to rest position, an eccentric cam oscillatably mounted on said power arm adapted when engaged with said roll to drive said power arm and type bar to print position, a spring connected between said power arm and cam normally biasing said carn from engagement with said power driven roll, and a bell crank pivotally mounted on said frame and adapted to be rocked by said key lever when the latter is depressed, the improvement comprising:

a cam latching element pivotally mounted on said power arm and spring biased to positively latch said cam from accidental engagement with said power roll, said element including an operating lug normally positioned to be engaged by said bell crank thereby to rock and unlatch said cam when said bell crank is rocked, said element further including a cam drive lug positioned to positively engage and rock said unlatched cam into power roll engagement as said element is rocked beyond its carn latching position.

2. In a type bar action for an electric typewriter including a power driven roll, a frame, a key lever pivotally mounted on said frame, a type bar pivotally mounted for movement from a rest position to a print position, a movable power arm pivotally mounted on said frame, a link connecting said type bar with said power arm, a return spring biasing said power arm and type bar to rest position, an eccentric cam adapted when engaged with said power roll to drive said power arm and type bar to print position, a spring connected between said power arm and cam biasing said cam from engagement with said power driven roll, and a bell crank pivotally mounted on said frame and adapted to be rocked by said key lever when the latter is depressed, the improvement comprising:

a combined cam latching and cam driving lever pivotally mounted on said power arm and normally biased to engage and latch said cam,

an operating lug on said combined cam latching and cam driving lever,

a shoulder on said bell crank adapted to normally overlie said operating lug whereby said lever is rocked by said bell crank in response to depression of said key lever to unlatch said cam,

and means on said lever adapted to engage and positively rock said unlatched cam into operative engagement with said power roll as said lever is rocked beyond its cam latching position.

3. The type bar action as recited in claim 2, further including means to disengage said cam from said power roll after a predetermined drive interval, whereby said cam and lever are restored to normal latched positions, the position of said operating lug in normal position relative to said bell crank shoulder precluding a repeat action until the key lever is restored and redepressed.

References Cited by the Examiner UNITED STATES PATENTS 2,407,195 9/ 1946 Von Reppert 19717 2,717,685 9/1955 Buhler 197-17 2,807,345 9/1957 Mimlitch 197-17 2,868,345 1/1959 Nitschke 197-47 2,889,025 6/1959 Lambert 19717 2,897,941 8/1959 Dodge 197--17 2,931,481 4/1960 Salto 197-17 2,938,615 5/1960 Donnan et al 197-17 3,225,884 12/1965 Krauss et al. 197-17 ROBERT E. PULFREY, Primary Examiner.

E. S. BURR, Assistant Examiner. 

1. IN A TYPE BAR ACTION FOR AN ELECTRIC TYPEWRITER INCLUDING A POWER DRIVEN ROLL, A FRAME, A KEY LEVER PIVOTALLY MOUNTED ON SAID FRAME, A TYPE BAR PIVOTALLY MOUNTED FOR MOVEMENT FROM A REST POSITION TO A PRINT POSITION, A MOVABLE POWER ARM PIVOTALLY MOUNTED ON SAID FRAME, A LINK CONNECTING SAID TYPE BAR WITH SAID POWER ARM, A RETURN SPRING BIASING SAID POWER ARM AND TYPE BAR TO REST POSITION, AN ECCENTRIC CAM OSCILLATABLY MOUNTED ON SAID POWER ARM ADAPTED WHEN ENGAGED WITH SAID ROLL TO DRIVE SAID POWER ARM AND TYPE BAR TO PRINT POSITION, A SPRING CONNECTED BETWEEN SAID POWER ARM AND CAM NORMALLY BIASING SAID CAM FROM ENGAGEMENT WITH SAID POWER DRIVEN ROLL, AND A BELL CRANK PIVOTALLY MOUNTED ON SAID FRAME AND ADAPTED TO BE ROCKED BY SAID KEY LEVER WHEN THE LATTER IS DEPRESSED, THE IMPROVEMENT COMPRISING: 